BAEL-928 Introduction to drools (#1842)

* BAEL-804  A guide to Spring Drools

* BAEL-804  A guide to Spring Drools

* BAEL-804  A guide to Spring Drools

* BAEL-928 Introduction to Drools

* BAEL-928 Introduction to Drools

drools/pom.xml

@@ -0,0 +1,84 @@
+<?xml version="1.0" encoding="UTF-8"?>
+<project xmlns="http://maven.apache.org/POM/4.0.0"
+         xmlns:xsi="http://www.w3.org/2001/XMLSchema-instance"
+         xsi:schemaLocation="http://maven.apache.org/POM/4.0.0 http://maven.apache.org/xsd/maven-4.0.0.xsd">
+    <modelVersion>4.0.0</modelVersion>
+
+    <groupId>com.baeldung</groupId>
+    <artifactId>drools</artifactId>
+    <version>1.0.0-SNAPSHOT</version>
+    <properties>
+        <http-component-version>4.4.6</http-component-version>
+        <drools-version>7.0.0.CR1</drools-version>
+        <apache-poi-version>3.13</apache-poi-version>
+        <surefire-plugin-version>2.19.1</surefire-plugin-version>
+        <junit-version>4.11</junit-version>
+    </properties>
+    <dependencies>
+        <dependency>
+            <groupId>org.apache.httpcomponents</groupId>
+            <artifactId>httpcore</artifactId>
+            <version>${http-component-version}</version>
+        </dependency>
+        <!-- ... -->
+        <dependency>
+            <groupId>org.kie</groupId>
+            <artifactId>kie-ci</artifactId>
+            <version>${drools-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.drools</groupId>
+            <artifactId>drools-decisiontables</artifactId>
+            <version>${drools-version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.drools</groupId>
+            <artifactId>drools-core</artifactId>
+            <version>${drools-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.drools</groupId>
+            <artifactId>drools-compiler</artifactId>
+            <version>${drools-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>org.apache.poi</groupId>
+            <artifactId>poi</artifactId>
+            <version>${apache-poi-version}</version>
+        </dependency>
+
+        <dependency>
+            <groupId>org.apache.poi</groupId>
+            <artifactId>poi-ooxml</artifactId>
+            <version>${apache-poi-version}</version>
+        </dependency>
+        <dependency>
+            <groupId>junit</groupId>
+            <artifactId>junit</artifactId>
+            <version>${junit-version}</version>
+            <scope>test</scope>
+        </dependency>
+        <dependency>
+            <groupId>org.springframework</groupId>
+            <artifactId>spring-core</artifactId>
+            <version>4.3.6.RELEASE</version>
+        </dependency>
+
+    </dependencies>
+    <build>
+        <plugins>
+            <plugin>
+                <groupId>org.apache.maven.plugins</groupId>
+                <artifactId>maven-surefire-plugin</artifactId>
+                <version>${surefire-plugin-version}</version>
+                <configuration>
+                    <excludes>
+                        <exclude>**/*IntegrationTest.java</exclude>
+                    </excludes>
+                </configuration>
+            </plugin>
+        </plugins>
+    </build>
+
+</project>

drools/src/main/java/com/baeldung/drools/config/DroolsBeanFactory.java

@@ -0,0 +1,67 @@
+package com.baeldung.drools.config;
+
+import org.kie.api.KieServices;
+import org.kie.api.builder.*;
+import org.kie.api.io.KieResources;
+import org.kie.api.runtime.KieContainer;
+import org.kie.api.runtime.KieSession;
+import org.kie.internal.io.ResourceFactory;
+import java.io.IOException;
+import java.util.Arrays;
+import java.util.List;
+
+public class DroolsBeanFactory {
+
+    private static final String RULES_PATH = "com/baeldung/drools/rules/";
+    private KieServices kieServices=KieServices.Factory.get();
+
+    private  KieFileSystem getKieFileSystem() throws IOException{
+        KieFileSystem kieFileSystem = kieServices.newKieFileSystem();
+        List<String> rules=Arrays.asList("SuggestApplicant.drl","Product_rules.xls");
+        for(String rule:rules){
+            kieFileSystem.write(ResourceFactory.newClassPathResource(rule));
+        }
+        return kieFileSystem;
+
+    }
+
+    public KieContainer getKieContainer() throws IOException {
+        getKieRepository();
+
+        KieBuilder kb = kieServices.newKieBuilder(getKieFileSystem());
+        kb.buildAll();
+
+        KieModule kieModule = kb.getKieModule();
+        KieContainer kContainer = kieServices.newKieContainer(kieModule.getReleaseId());
+
+        return kContainer;
+
+    }
+
+    private void getKieRepository() {
+        final KieRepository kieRepository = kieServices.getRepository();
+        kieRepository.addKieModule(new KieModule() {
+                        public ReleaseId getReleaseId() {
+                return kieRepository.getDefaultReleaseId();
+            }
+        });
+    }
+
+    public KieSession getKieSession(){
+        getKieRepository();
+        KieFileSystem kieFileSystem = kieServices.newKieFileSystem();
+
+        kieFileSystem.write(ResourceFactory.newClassPathResource("com/baeldung/drools/rules/SuggestApplicant.drl"));
+        kieFileSystem.write(ResourceFactory.newClassPathResource("com/baeldung/drools/rules/Product_rules.xls"));
+
+        KieBuilder kb = kieServices.newKieBuilder(kieFileSystem);
+        kb.buildAll();
+        KieModule kieModule = kb.getKieModule();
+
+        KieContainer kContainer = kieServices.newKieContainer(kieModule.getReleaseId());
+
+        return kContainer.newKieSession();
+
+    }
+
+}

drools/src/main/java/com/baeldung/drools/model/Applicant.java

@@ -0,0 +1,48 @@
+package com.baeldung.drools.model;
+
+public class Applicant {
+
+    private String name;
+    private int age;
+    private double currentSalary;
+    private int experienceInYears;
+
+    public Applicant(String name, int age, Double currentSalary, int experienceInYears) {
+        this.name = name;
+        this.age = age;
+        this.currentSalary = currentSalary;
+        this.experienceInYears = experienceInYears;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public int getAge() {
+        return age;
+    }
+
+    public void setAge(int age) {
+        this.age = age;
+    }
+
+    public Double getCurrentSalary() {
+        return currentSalary;
+    }
+
+    public void setCurrentSalary(Double currentSalary) {
+        this.currentSalary = currentSalary;
+    }
+
+    public int getExperienceInYears() {
+        return experienceInYears;
+    }
+
+    public void setExperienceInYears(int experienceInYears) {
+        this.experienceInYears = experienceInYears;
+    }
+}

drools/src/main/java/com/baeldung/drools/model/Product.java

@@ -0,0 +1,38 @@
+package com.baeldung.drools.model;
+
+public class Product {
+    private String name;
+    private String type;
+
+    private String label;
+
+    public Product(String name, String type) {
+        this.name = name;
+        this.type = type;
+    }
+
+    public String getName() {
+        return name;
+    }
+
+    public void setName(String name) {
+        this.name = name;
+    }
+
+    public String getType() {
+        return type;
+    }
+
+    public void setType(String type) {
+        this.type = type;
+    }
+
+    public String getLabel() {
+        return label;
+    }
+
+    public void setLabel(String label) {
+        this.label = label;
+    }
+
+}

drools/src/main/java/com/baeldung/drools/model/SuggestedRole.java

@@ -0,0 +1,14 @@
+package com.baeldung.drools.model;
+
+public class SuggestedRole {
+
+    private String role;
+
+    public String getRole() {
+        return role;
+    }
+
+    public void setRole(String role) {
+        this.role = role;
+    }
+}

drools/src/main/java/com/baeldung/drools/service/ApplicantService.java

@@ -0,0 +1,23 @@
+package com.baeldung.drools.service;
+
+import com.baeldung.drools.config.DroolsBeanFactory;
+import com.baeldung.drools.model.Applicant;
+import com.baeldung.drools.model.SuggestedRole;
+import org.kie.api.runtime.KieContainer;
+import org.kie.api.runtime.KieSession;
+
+import java.io.IOException;
+
+public class ApplicantService {
+
+    KieSession kieSession=new DroolsBeanFactory().getKieSession();
+
+    public SuggestedRole suggestARoleForApplicant(Applicant applicant,SuggestedRole suggestedRole) throws IOException {
+        kieSession.insert(applicant);
+        kieSession.setGlobal("suggestedRole",suggestedRole);
+        kieSession.fireAllRules();
+        System.out.println(suggestedRole.getRole());
+        return  suggestedRole;
+
+    }
+}

drools/src/main/java/com/baeldung/drools/service/ProductService.java

@@ -0,0 +1,20 @@
+package com.baeldung.drools.service;
+
+import com.baeldung.drools.config.DroolsBeanFactory;
+import com.baeldung.drools.model.Product;
+import org.kie.api.runtime.KieContainer;
+import org.kie.api.runtime.KieSession;
+
+public class ProductService {
+
+    private KieSession kieSession=new DroolsBeanFactory().getKieSession();
+
+    public Product applyLabelToProduct(Product product){
+        kieSession.insert(product);
+        kieSession.fireAllRules();
+        System.out.println(product.getLabel());
+        return  product;
+
+    }
+
+}

drools/src/main/resources/com/baeldung/drools/rules/SuggestApplicant.drl

@@ -0,0 +1,31 @@
+package com.baeldung.drools.rules;
+
+import com.baeldung.drools.model.Applicant;
+
+global com.baeldung.drools.model.SuggestedRole suggestedRole;
+
+dialect  "mvel"
+
+rule "Suggest Manager Role"
+    when
+        Applicant(experienceInYears > 10)
+        Applicant(currentSalary > 1000000 && currentSalary <= 2500000)
+    then
+        suggestedRole.setRole("Manager");
+end
+
+rule "Suggest Senior developer Role"
+    when
+        Applicant(experienceInYears > 5 && experienceInYears <= 10)
+        Applicant(currentSalary > 500000 && currentSalary <= 1500000)
+    then
+        suggestedRole.setRole("Senior developer");
+end
+
+rule "Suggest Developer Role"
+    when
+        Applicant(experienceInYears > 0 && experienceInYears <= 5)
+        Applicant(currentSalary > 200000 && currentSalary <= 1000000)
+    then
+        suggestedRole.setRole("Developer");
+end

drools/src/test/java/com/baeldung/drools/service/ApplicantServiceIntegrationTest.java

@@ -0,0 +1,53 @@
+package com.baeldung.drools.service;
+
+import com.baeldung.drools.model.Applicant;
+import com.baeldung.drools.model.SuggestedRole;
+import org.junit.Before;
+import org.junit.Test;
+
+import java.io.IOException;
+
+import static junit.framework.Assert.assertNull;
+import static junit.framework.TestCase.assertEquals;
+
+
+public class ApplicantServiceIntegrationTest {
+
+
+    private ApplicantService applicantService;
+
+    @Before
+    public void setup(){
+        applicantService = new ApplicantService();
+    }
+
+    @Test
+    public void whenCriteriaMatching_ThenSuggestManagerRole() throws IOException {
+        Applicant applicant=new Applicant("Davis",37,1600000.0,11);
+        SuggestedRole suggestedRole=new SuggestedRole();
+        applicantService.suggestARoleForApplicant(applicant,suggestedRole);
+        assertEquals("Manager",suggestedRole.getRole());
+    }
+
+    @Test
+    public void whenCriteriaMatching_ThenSuggestSeniorDeveloperRole() throws IOException {
+        Applicant applicant=new Applicant("John",37,1200000.0,8);
+        SuggestedRole suggestedRole=new SuggestedRole();
+        applicantService.suggestARoleForApplicant(applicant,suggestedRole);
+        assertEquals("Senior developer",suggestedRole.getRole());
+    }
+    @Test
+    public void whenCriteriaMatching_ThenSuggestDeveloperRole() throws IOException {
+        Applicant applicant=new Applicant("Davis",37,800000.0,3);
+        SuggestedRole suggestedRole=new SuggestedRole();
+        applicantService.suggestARoleForApplicant(applicant,suggestedRole);
+        assertEquals("Developer",suggestedRole.getRole());
+    }
+    @Test
+    public void whenCriteriaNotMatching_ThenNoRole() throws IOException {
+        Applicant applicant=new Applicant("John",37,1200000.0,5);
+        SuggestedRole suggestedRole=new SuggestedRole();
+        applicantService.suggestARoleForApplicant(applicant,suggestedRole);
+        assertNull(suggestedRole.getRole());
+    }
+}

drools/src/test/java/com/baeldung/drools/service/ProductServiceIntegrationTest.java

@@ -0,0 +1,32 @@
+package com.baeldung.drools.service;
+
+import com.baeldung.drools.model.Product;
+import org.junit.Before;
+import org.junit.Test;
+import static junit.framework.TestCase.assertEquals;
+
+
+public class ProductServiceIntegrationTest {
+
+    private ProductService productService;
+
+    @Before
+    public void setup(){
+        productService=new ProductService();
+    }
+
+
+    @Test
+    public void whenProductTypeElectronic_ThenLabelBarcode(){
+        Product product=new Product("Microwave","Electronic");
+        product=productService.applyLabelToProduct(product);
+        assertEquals("BarCode",product.getLabel());
+    }
+
+    @Test
+    public void whenProductTypeBook_ThenLabelIsbn(){
+        Product product=new Product("AutoBiography","Book");
+        product=productService.applyLabelToProduct(product);
+        assertEquals("ISBN",product.getLabel());
+    }
+}

pom.xml

@@ -221,6 +221,7 @@
         <module>spring-data-gemfire</module>
         <module>mybatis</module>
         <module>spring-drools</module>
+        <module>drools</module>
     </modules>
 
     <dependencies>